I heard the Messenger of Allah (ﷺ) say: He who lets his garment trail during prayer out of pride, Allah, the Almighty, has nothing to do with pardoning him and protecting him from Hell.
Sunan Abi Dawud Book 2, Hadith 247
← Previous Hadith The Messenger of Allah (ﷺ) prohibited us to pray in a sheet of cloth without crossing both its ends, and he also prohibited us to pray in a wrapper without putting on a sheet.

Sunan Abi Dawud Book 2, Hadith 246 Next Hadith → while a man was praying letting his lower garment trail, the Messenger of Allah (ﷺ) said to him: Go and perform ablution. He, therefore, went and performed ablution and then returned. He (the prophet) again said: Go and perform ablution. He again went, performed ablution and returned. A man said to him (the prophet): Messenger of Allah, why did you order him to perform ablution? He said: he was praying with lower garment trailing, and does not accept the prayer of a man who lets his lower garment trail.

Sunan Abi Dawud Book 2, Hadith 248